Outlook 2003 - How to open reply in same wind

I believe I used to hit 'Reply' in Outlook and it would use that same message to allow me to reply.. now it opens a new window.. leaving the original message in it's own window. How do I make Outlook open a reply in the same window?

The information on Computing.Net is the opinions of its users. Such
opinions may not be accurate and they are to be used at your own risk.
Computing.Net cannot verify the validity of the statements made on this
site. Computing.Net and Compnet Ventures, LLC hereby disclaim all responsibility
and liability for the content of Computing.Net and its accuracy.